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<html>
  <head>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Add Head</title>
    <link rel="stylesheet" href="doc.css">
  </head>
  <body>
<!--#include virtual="_header.html" -->


  <div id=content>
<h1>Add Head</h1>



<h2>Configuration</h2>
<p>
The 'Add Head' filter is enabled by specifying:
<dl>
  <dt>Apache:<dd><pre class="prettyprint"
     >ModPagespeedEnableFilters add_head</pre>
  <dt>Nginx:<dd><pre class="prettyprint"
     >pagespeed EnableFilters add_head;</pre>
</dl>
<p>
in the configuration file, but it is also enabled automatically by several
other filters, including combine_heads, move_css_to_head, and
add_instrumentation.
</p>

<h2>Description</h2>
<p>
The 'Add Head' filter is very simple: it adds a head to the document if it
encounters a &lt;body&gt; tag before finding a &lt;head&gt; tag.
</p>
<p>
For example, if the HTML document looks like this:
</p>
<pre class="prettyprint">
&lt;html&gt;
  &lt;body&gt;
    &lt;div class="blue yellow big bold"&gt;
      Hello, world!
    &lt;/div&gt;
  &lt;/body&gt;
&lt;/html&gt;
</pre>
<p>
Then PageSpeed will rewrite it into:
</p>
<pre class="prettyprint">
&lt;html&gt;
  &lt;head&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div class="blue yellow big bold"&gt;
      Hello, world!
    &lt;/div&gt;
  &lt;/body&gt;
&lt;/html&gt;
</pre>

<h2>Note</h2>
<p>
This filter exists primarily to ensure that other filters have a place
to insert new tags that needs to be in the head, or that trigger on
the closing-tag for a head to perform some other action.
</p>

<h2>Risks</h2>
<p>
This filter is considered minimal risk.
</p>


  </div>
  <!--#include virtual="_footer.html" -->
  </body>
</html>
